The present invention relates to optical card readers. As used herein, the term "optical card reader" refers to apparatus adapted to process opaque cards which are punched or apertured at predetermined locations on a matrix or gridwork so that at each intersection of the grid an aperture comprises one binary signal and the absence of an aperture forms the complementary binary signal. Light is incident on one side of the card, and photodetectors are positioned on the other side of the card to detect light passing through an associated aperture. In the present invention, the gridwork will be referred to as having rows (which extend the width of the card) and columns (which extend lengthwise of the card--i.e., the direction in which the card moves or is processed). The system includes a plurality of photodetectors which are spaced laterally to coincide with the spacing of the columns on the card. Hence, as the card passes over the photodetectors, light either shines through an aperture or is blocked by the absence of an aperture; and each photodetector thereby exhibits a relatively low resistance (logical "0") or a high resistance (logical "1" ). The designators are arbitrary and can be interchanged. Bias voltages are connected in circuit with the detectors for generating the actual signals in a conventional manner.
The present apparatus is designed primarily for use in an order-placing system wherein the ordering information, including quantity and product designation, are transmitted via existing telephone lines to a central computer which receives and processes the order. The subscriber has a number of punched plastic cards, and each card is punched so as to order a specific item. Once the purchaser has decided what it is he desires to order, he simply selects the proper cards from a store of cards corresponding to the various items that could possibly be ordered, and he places those cards in a card reader. After establishing contact with the computer through a local telephone hand set and associated terminal equipment, the cards are then read by the optical card reader and the information stored on the cards is converted to signal tones which are transmitted via the telephone line to the computer.
The processing of individual cards is controlled by a return signal from the computer to the remote subscriber responsive to the detection of an "End-of-Card" character on each card and the verification of data transmitted. Thus, the card reader is responsive to a signal transmitted from the computer for initiating the processing of each subsequent card. The remote subscriber apparatus for establishing communication with the computer, converting the binary signals to tones, and performing the other necessary processing is disclosed in copending application for "Electronic Order Placement System using Tone Signals Over Telephone Line" of Eitzen and Johnson, Ser. No. 804,884, filed June 9, 1977, and the disclosure of that application is incorporated herein by reference.
The apparatus of the present invention includes a supply or input hopper for storing the selected cards in a vertical stack. A solenoid-actuated plunger moves the bottom card from beneath the stack upon signal. A drive mechanism engages the bottom card and moves it along a reading path to a reading station.
The card drive mechanism includes a floating transport equipped with endless tracks (which may be formed from elastomeric O-rings) which rides on top of the cards while driving them along the reading path. The transport is loaded downwardly by means of springs which exert a substantially constant downward force on the transport, thereby resulting in a uniform force moving the cards. Each card is moved continuously once it is started in the reading path, and the stack of cards is read seriatim. An array of optical detectors arranged in register with the columns on the cards is located beneath the cards as they pass through the reading station. A lens is carried by the transport for illuminating each card along a line parallel to the rows of apertures on the card. As the photodetectors beneath the cards are illuminated by light passing through the apertures in the cards (or not illuminated, as the case may be), binary electrical signals are generated by the photodetectors representative of the information on the cards.
As the cards pass to the end of the reading path, they fall into a bin where they are collected until all of the cards are read. After an order is placed, the purchaser may return the cards to their original storage locations.
The present invention thus provides a simple and economical optical reader for storing and reading a stack of cards in sequence while moving the cards continuously over a set of photodetectors for converting the punched information on the cards to corresponding binary electrical signals.
Other features and advantages of the present invention will be apparent to persons skilled in the art from the following detailed description of a preferred embodiment accompanied by the attached drawing wherein identical reference numerals will refer to like parts in the various views.